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Assignment #1

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Article - Peptidoglycan

Critique - Most parts of the article material are relevant to the topic, although sentences like the last sentence in the first paragraph of "Structure" is not necessary to put it there. The article is neutral without any biases, and referenced are provided so that we can verify the sources, but some of the references are not reliable. For example, one of the references comes from another encyclopedia page, which cannot be considered reliable. Besides, one statement in lead section is cited with an animation website, which is not reliable as well. The article has a clear structure and a good order of important information, but the subsection "Biosynthesis" relies too much on a single reference. Also, this section is unbalance because it talks about every single step in the first stage of PG synthesis but only few sentences for the rest of the stages. This means that one stage is overrepresented, and the rest are underrepresented. Furthermore, one of the hyperlink (9) that I checked could not open the page, so it is a good idea to replace the link with an accessible one. I did not see close paraphrasing or plagiarism for the links that I checked, and there is no out-of-date or missing information since PG is the basis of bacteria. Lastly, there is only one editor talks in the talk page, which means the topic is not actively discussed.

Charlene yjy (talk) 20:56, 17 September 2017 (UTC)[reply]

Assignment #2

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Microbial ecology includes numerous symbiosis between microbes and other species, and some symbiotic relationships are essential for living. As other species, even humans cannot live without microbial symbiosis, this section is notable to stay in the article. Therefore, more details, explanation, or examples should be given under this subtitle. This "Symbiosis" section has to improve because it needs to show people how symbiosis work in the microbial ecology so that people realize the importance of symbiosis in the environment and in their lives. It is not enough to write several sentences, stating that symbiosis is important for ecosystem. Besides, the example used under this section is not appropriate because although chloroplast is evolved from cyanobacteria through endosymbiosis, chloroplast is now considered as an organeele in plants, so this cannot be considered as symbiosis. So, I will improve this section through adding several examples that can show the importance of microbial symbiosis, and can help people understand how microbial symbiosis work.

There are two types of symbiosis: ectosymbiosis and endosymbiosis. One example that is ectosymbiosis and shows the importance of microbial symbiosis to life is the cow's rumen. If there is no microbe living in cow's rumen, it will not be able to break down cellulose in plants that it eat, and it cannot absorb glucose into its blood, and it will die eventually without absorbing energy.[1]

Microbial symbiosis also has great impact on the environment, especially for biogeochemical cycles like nitrogen cycle and carbon cycle. An important endosymbiosis for nitrogen cycle is the symbiosis between Rhizobium and legumes. It is an important symbiosis because legumes need nitrogen for growth, but they cannot use nitrogen gas as the nitrogen source. While Rhizobium can fix nitrogen, but they need energy for ATP synthesis and electrons for NADPH synthesis.[2] Plants use atmospheric CO2 to assimilate organic carbon, which Rhizobium use as energy and electron source for ATP and NADPH. NH4+ produced as the waste product of Rhizobium can supply legumes with sufficient nitrogen source, and non-legume crop can use NH4+ from the decomposed leguminous plant.[3]

  1. ^ ELLIS, J. L.; DIJKSTRA, J.; KEBREAB, E.; BANNINK, A.; ODONGO, N. E.; McBRIDE, B. W.; FRANCE, J. (26 March 2008). "Aspects of rumen microbiology central to mechanistic modelling of methane production in cattle". The Journal of Agricultural Science. 146 (02). doi:10.1017/S0021859608007752. {{cite journal}}: no-break space character in |first1= at position 3 (help); no-break space character in |first5= at position 3 (help); no-break space character in |first6= at position 3 (help)
  2. ^ Mylona, P. (1 July 1995). "Symbiotic Nitrogen Fixation". THE PLANT CELL ONLINE. 7 (7): 869–885. doi:10.1105/tpc.7.7.869.
  3. ^ Lodwig, E. M.; Hosie, A. H. F.; Bourdès, A.; Findlay, K.; Allaway, D.; Karunakaran, R.; Downie, J. A.; Poole, P. S. (17 April 2003). "Amino-acid cycling drives nitrogen fixation in the legume–Rhizobium symbiosis". Nature. 422 (6933): 722–726. doi:10.1038/nature01527.

Charlene yjy (talk) 21:49, 26 September 2017 (UTC)[reply]

Assignment #3: Original - Microbial ecology ("Symbiosis" section)

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Microbes, especially bacteria, often engage in symbiotic relationships (either positive or negative) with other organisms, and these relationships affect the ecosystem. One example of these fundamental symbioses are chloroplasts, which allow eukaryotes to conduct photosynthesis. Chloroplasts are considered to be endosymbiotic cyanobacteria, a group of bacteria that are thought to be the origins of aerobic photosynthesis. Some theories state that this invention coincides with a major shift in the early earth's atmosphere, from a reducing atmosphere to an oxygen-rich atmosphere. Some theories go as far as saying that this shift in the balance of gases might have triggered a global ice-age known as the Snowball Earth [citation needed].

Assignment #3: Edit - Microbial ecology ("Symbiosis" section)

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Microbial symbiosis is important to the living of all creatures, and it has an impact to the environment.

There are two types of symbiosis: ectosymbiosis and endosymbiosis. Rumen is an example of ectosymbiosis, and microbes in the rumen are essential to cows' lives. Microbial enzymes can breakdown cellulose, while mammalian enzymes cannot. The end product, glucose, is not directly absorbed by the cow. Instead, anaerobic rumen microbes ferment glucose, and the fermentation waste products, for example, volatile fatty acids, are absorbed into cows' blood, and these waste products are the main sources of energy and electrons.[1] However, methane as a waste product from methogenic Archaea in the rumen is a greenhouse gas, which affects the global warming.[2]

Microbial symbiosis also has great impact on the environment, especially for biogeochemical cycles like nitrogen cycle.[3] An important endosymbiosis for nitrogen cycle is the symbiosis between Rhizobium and legumes. Plants need nitrogen for growth, but they cannot use atmospheric nitrogen as an nitrogen source. While bacteria can fix atmospheric nitrogen, but they cannot produce sufficient energy for nitrogen fixation. Legume roots secrete a chemical which attracts Rhizobium, then they form a new compartment: root nodule. Rhizobium then differentiate into endosymbiotic bacteroid that performs N-fixation.[4] With a plant-derived membrane, bacteroid and legumes cooperate to synthesize leghemoglobin that stores oxygen, so that nitrogenase can carry out nitrogen fixation and produce ammonium.[5] Ammonium is a fertilizer, and as leguminous plants decompose, non-legume crops can use ammonium as well.

  1. ^ Lourenço, M.; Ramos-Morales, E.; Wallace, R. J. (23 March 2010). "The role of microbes in rumen lipolysis and biohydrogenation and their manipulation". animal. 4 (07): 1008–1023. doi:10.1017/S175173111000042X.
  2. ^ ELLIS, J. L.; DIJKSTRA, J.; KEBREAB, E.; BANNINK, A.; ODONGO, N. E.; McBRIDE, B. W.; FRANCE, J. (26 March 2008). "Aspects of rumen microbiology central to mechanistic modelling of methane production in cattle". The Journal of Agricultural Science. 146 (02). doi:10.1017/S0021859608007752. {{cite journal}}: no-break space character in |first1= at position 3 (help); no-break space character in |first5= at position 3 (help); no-break space character in |first6= at position 3 (help)
  3. ^ Lodwig, E. M.; Hosie, A. H. F.; Bourdès, A.; Findlay, K.; Allaway, D.; Karunakaran, R.; Downie, J. A.; Poole, P. S. (17 April 2003). "Amino-acid cycling drives nitrogen fixation in the legume–Rhizobium symbiosis". Nature. 422 (6933): 722–726. doi:10.1038/nature01527.
  4. ^ Mylona, P. (1 July 1995). "Symbiotic Nitrogen Fixation". THE PLANT CELL ONLINE. 7 (7): 869–885. doi:10.1105/tpc.7.7.869.
  5. ^ Sainz, Martha; Calvo-Begueria, Laura; Pérez-Rontomé, Carmen; Wienkoop, Stefanie; Abián, Joaquín; Staudinger, Christiana; Bartesaghi, Silvina; Radi, Rafael; Becana, Manuel (March 2015). "Leghemoglobin is nitrated in functional legume nodules in a tyrosine residue within the heme cavity by a nitrite/peroxide-dependent mechanism". The Plant Journal. 81 (5): 723–735. doi:10.1111/tpj.12762.

Charlene yjy (talk) 02:49, 8 October 2017 (UTC)[reply]

Peer Review

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The edit for the section clearly elaborates on the two types of microbial symbiosis while also emphasizing the topic and each example’s environmental significance. The section is clearly divided for the two examples it elaborates on and the overall structure is well-defined. However, it may be helpful to precede the in-depth examples by defining symbiosis and the 2 types that will be focussed on in order to identify their differences before diving into the examples. Symbiosis is also a general term that can be separated into other types of interactions such as commensalism, mutualism, and parasitism, so these topics should also be addressed and discussed if possible.

Both examples in the current draft are concise and well-written, but the details may be difficult to understand for readers without prior knowledge of microbial ecology. For example, while discussing ectosymbiosis in rumen, volatile fatty acids as sources of energy and electrons is mentioned. This part may be more easily comprehended if a brief explanation of the significance of energy and electron sources is included (such as their role in respiration and metabolism). Doing so can clarify and further emphasize the mechanisms involved in the symbiotic relationship.

The current draft possesses very neutral language and references respectable sources of literature such as the Journal of Agricultural Science. A suggestion is that although the current unedited section of symbiosis is before the ‘Roles’ section, perhaps it can be moved to follow ‘Roles’. Since that part outlines some of the types of biogeochemical cycles that symbiosis relationships play a part in, the text may flow more naturally from describing the roles of microbial ecology to symbiosis rather than the other way around.

Ezqsun (talk) 07:59, 6 November 2017 (UTC)[reply]

Assignment #5

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Microbial symbiosis is the long-term interaction between two organisms. It affects the ecosystem, and it is important to the living of all organisms. Based on where the symbiont is found, microbial symbiosis is categorized into two types: endosymbiosis and ectosymbiosis, and they are either mutualistic, commensalistic, or parasitic.

Microbial symbiosis has great impacts on the environment, especially biogeochemical cycles like nitrogen cycle.[1] Endosymbiosis is the living of one organism within another organism's cells, and the symbiotic relationship between Rhizobium and legumes is a typical example. Rhizobium infects root cells of legumes, forming a new compartment: root nodule. Rhizobium then differentiate into endosymbiotic bacteroid that performs nitrogen fixation to help plants grow because plants cannot use atmospheric nitrogen as a nitrogen source.[2] Ammonium, which is a fertilizer, is also produced during nitrogen fixation. When leguminous plants decompose, non-legume crops can use those ammonium as their nitrogen source.

Ectosymbiosis is the living of the symbiont on the body surface of the host. One example is the microbes that live on the surface of cow's rumen. They are essential to cows because microbial enzymes can breakdown cellulose, while mammalian enzymes cannot. Cows can only use the fermentation waste products produced by anaerobic rumen microbes for metabolic processes such as energy conservation and synthesis of nutrients.[3] However, methane is a greenhouse gas which affects the global warming, and it is produced by methogenic Archaea in the rumen.[4]

  1. ^ Lodwig, E. M.; Hosie, A. H. F.; Bourdès, A.; Findlay, K.; Allaway, D.; Karunakaran, R.; Downie, J. A.; Poole, P. S. (17 April 2003). "Amino-acid cycling drives nitrogen fixation in the legume–Rhizobium symbiosis". Nature. 422 (6933): 722–726. doi:10.1038/nature01527.
  2. ^ Mylona, P. (1 July 1995). "Symbiotic Nitrogen Fixation". THE PLANT CELL ONLINE. 7 (7): 869–885. doi:10.1105/tpc.7.7.869.
  3. ^ Lourenço, M.; Ramos-Morales, E.; Wallace, R. J. (23 March 2010). "The role of microbes in rumen lipolysis and biohydrogenation and their manipulation". animal. 4 (07): 1008–1023. doi:10.1017/S175173111000042X.
  4. ^ ELLIS, J. L.; DIJKSTRA, J.; KEBREAB, E.; BANNINK, A.; ODONGO, N. E.; McBRIDE, B. W.; FRANCE, J. (26 March 2008). "Aspects of rumen microbiology central to mechanistic modelling of methane production in cattle". The Journal of Agricultural Science. 146 (02). doi:10.1017/S0021859608007752.

Charlene yjy (talk) 00:49, 20 November 2017 (UTC)[reply]

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